This invention relates to heat exchangers and liquid/gas separators, and more particularly, to condensers and liquid/gas separators which are used together for separating a condensate from a gas flow in a fuel cell system.
It is known to employ a condenser in a fuel cell system to condense water from the cathode exhaust gas flow, in combination with a liquid/gas separator downstream of the condenser to separate the condensed water from the cathode exhaust gas flow after it has passed through the condenser. The recovery of water from the cathode exhaust gas flow is desirable because the water can then be used for the purpose of humidifying the fuel cell inlet gases, performing evaporative cooling of inlet gases, and/or supplying water for the various chemical reactions that occur within a hydrocarbon fuel processing system. U.S. Pat. No. 6,015,634 issued Jan. 18, 2000 to Bonville, Jr. et al. shows one example of a fuel cell system employing a condenser and liquid/gas separator. It is also known to employ condensers and liquid/gas separators to separate an electrolyte, since its phosphoric acid, from a gas flow in a fuel cell system. U.S. Pat. No. 4,372,759 issued Aug. 28, 1981 to Sederquist et al. shows one example of such a system. While conventional systems may be suitable for their intended purpose, there is always room for improvement.
For example, because fuel cells offer advantages in efficiency and in emission, interest in utilizing fuel cells as electricity generating plants and/or as a power source for vehicles has been increasing as concerns grow over the supply of fossil-fuel and the environmental effects of conventional fossil-fuel power sources, such as internal combustion engines for vehicles. However, improvements in affordability and compactness may be required before fuel cells become acceptable for widespread usage, particularly in vehicles.
It is the principle object of the invention to provide a new and improved integrated condenser/separator for fuel cell exhaust gas.
It is another object of the invention to provide a relatively compact construction for a condenser and liquid/gas separator for fuel cell exhaust gas.
An exemplary embodiment of the invention achieves at least some of the foregoing objects in an integrated condenser/separator for condensing and separating a condensate from a cathode exhaust gas flow in a fuel cell system. The condenser/separator includes a housing, a baffle plate positioned in the housing to divide the interior of the housing into a first gas flow chamber and a second gas flow chamber, and a plurality of heat exchange units arranged as a first stack of the heat exchange units positioned in the first gas flow chamber and a second stack of the heat exchanger units positioned in the second gas flow chamber. The housing includes a gas flow inlet, a gas flow outlet, a condensate outlet, a coolant inlet, and coolant outlet. A coolant opening is provided in the baffle plate to allow a flow of coolant through the baffle plate, a gas flow opening is provided in the baffle plate to allow a gas flow through the baffle plate. A first condensate drain is provided in the first gas flow chamber to drain condensate from the first gas flow chamber. The first stack of heat exchange units includes a first plurality of coolant channels interleaved with a first plurality of gas flow channels, a first inlet manifold to direct coolant into the first plurality of coolant channels, a first outlet manifold to receive coolant from the first plurality of coolant channels, and a first gas flow manifold to communicate gas flow with the first plurality of gas flow channels. The second stack includes a second plurality of coolant channels interleaved with a second plurality of gas flow channels, a second inlet manifold to direct coolant into the second plurality of coolant channels, a second outlet manifold that receives coolant from the second plurality of coolant channels, and a second gas flow manifold to communicate gas flow with the second plurality of gas flow channels.
According to one embodiment, the first or second gas flow manifolds are aligned with the gas flow openings in the baffle plate so that the gas flow makes one pass through the first plurality of gas flow channels and another pass through the second plurality of gas flow channels.
In one embodiment, the gas flow inlet opens into the first gas flow chamber, and the first and second gas flow manifolds are aligned with the gas flow openings in the baffle plate so that the gas flow makes a first pass from the first gas flow chamber through the first plurality of gas flow channels to the first gas flow manifold, flows from the gas flow manifold to the second gas flow manifold, and makes a second pass from the second gas flow manifold through the second plurality of second gas flow channels to the second gas flow chamber.
According to one embodiment, a coalescing member is positioned upstream of the first and second plurality of gas flow channels.
In one embodiment, the integrated condenser/separator further includes a condensate manifold in fluid communication with the condensate outlet and the first condensate drain to direct condensate from the condensate drain to the condensate outlet. According to a further embodiment, the condensate manifold includes a wall that surrounds at least part of the first and second gas flow chambers to define an exterior surface of the housing.
According to one embodiment, the second outlet manifold and the first inlet manifold are aligned with the coolant opening in the baffle plate to allow coolant flow from the second outlet manifold to the first inlet manifold so that the coolant makes a pass through the second plurality of coolant channels and an additional pass through the first plurality of coolant channels.
In one embodiment, the baffle plate has an additional coolant opening, the first and second inlet manifolds are aligned with one of the coolant openings in the baffle plate to allow coolant flow between the first and second inlet manifolds, and the first and second outlet manifolds are aligned with the other coolant openings in the baffle to allow coolant flow between the first and second outlet manifolds.
According to one embodiment, each of the heat exchange units includes a pair of plates sealingly joined at peripheral edges to define a coolant channel in each of the heat exchange units, and the heat exchange units are spaced from each other to define the gas flow channels between the heat exchange units. Further, the heat exchange units include respective sets of interconnected openings defining the inlet manifolds, the outlet manifolds, and the gas flow manifolds.
In one embodiment, the integrated condenser/separator further includes a second baffle plate positioned in the housing to divide the interior of the housing into a third gas flow chamber adjacent to the second gas flow chamber, a second condensate drain in the second gas flow chamber to drain condensate from the second gas flow chamber, and a third stack of heat exchange units positioned in the third gas flow chamber. The second baffle plate has a second coolant opening to allow a flow of coolant through the second baffle plate, and a second gas flow opening to allow a gas flow through the second baffle plate. The third stack includes a third plurality of coolant channels interleaved with a third plurality of gas flow channels, a third inlet manifold to direct coolant into the third plurality of coolant channels, a third outlet manifold to receive coolant from the third plurality of coolant channels, and a third gas flow manifold to communicate gas flow with a third plurality of gas flow channels.
According to a further embodiment, the gas flow inlet opens into the first gas flow chamber, the first and second gas flow manifolds are aligned with the gas flow opening in the first baffle plate, and the third gas flow manifold is blocked by an imperforate portion of the second baffle plate so that the gas flow makes a first pass from the first gas flow chamber through the first plurality of gas flow channels to the first gas flow manifold, flows from the first gas flow manifold to the second gas flow manifold, makes a second pass from the second gas flow manifold through the second plurality of gas flow channels, flows through the gas flow opening in the second baffle plate to the third gas flow chamber, and makes a third pass from the third gas flow chamber through the third plurality of gas flow channels to the third gas flow manifold.
Other objects and advantages will become apparent from the following specification taken in connection with accompanying drawings.